Potential of biocontrol agents against Ganoderma lucidum causing basal stem rot in mesquite (Prosopis cineraria) growing in arid region of India

Abstract

The present study was undertaken to investigate relative potential of native biocontrol agents (BCAs) against Ganoderma lucidum causing root rot mortality in Indian mesquite. The disease is mostly prevalent in sandy soils where trees are raised under rainfed conditions. In addition a beetle damages the roots resulting in increasing vulnerability of host thereby making entry of the pathogen easy for infection. In on dual culture tests, root bit experiment and compatibility with insecticides revealed that all the three BCAs Trichoderma longibrachiatum, T. harzianum and Aspergillus nidulans significantly inhibited the mycelial growth of G. lucidum over control. Highest mycelial growth inhibition (47.6%) was recorded at 96 hrs. followed by 39.8 and 29.3% at 72 and 48 hrs., respectively in T. longibrachium. Cell free filtrates of T. longibrachium, T. harzianum and A. nudulans were found significantly superior in inhibiting the mycelium growth of G. lucidum over control. Even a low concentration (3 ml) of T. longibrachiatum was more effective in inhibiting Ganoderma mycelium compared to other BCAs. Both Prosopis juliflora compost and Onion residue compost amendments as a food substrates favored the growth of these BCAs, which ultimately reduced viability of Ganoderma colonized root bits of cowpea. Studies on compatibility between insecticides and BCAs suggested that T. longibrachiatum,T. harzianum and A. nidulans can be combined with phorate or chloropyriphos at variable concentrations if amended together in the partially infected or as a prophylactic measure in healthy trees. These studies demonstrate that there exists ample opportunity of using native BCAs against G. lucidum in managing root rot mortality in Khejri in Indian hot arid regions.